In present day cable television networks, programming content may be provided from various sources, including satellite broadcasts, upstream headend or control centers (e.g. via optical fiber), and from content storage facilities such as optical disks, magnetic disks, or even tape. In some situations the programming content may be loaded onto headend systems prior to distribution to subscribers. The headend systems may in turn provide the programming content as video and/or audio-on-demand.
Advertising may be inserted into the program content prior to the program content being delivered to subscriber systems. “Downstream” regional devices such as splicers and/or multiplexers may be applied in order to provide ad insertion into the program content. Downstream ad splicers/multiplexers tend to be complicated and expensive devices, and complicated and time-critical signaling may be involved between splicer/multiplexers and the video servers.